Machine for straightening tube bends



Dec. 27, 1960 y A. HUET 2,966,196

MACHINE FOR STRAIGHTENING TUBE BENDS Filed July 7, 1958 2 Sheets-Sheet 1 INVENTOR:

ANDRE HUET ATTORNEY Dec. 27, 1960 A. HUET 2,966,196

MACHINE FOR STRAIGHTENING TUBE BENDS Filed July 7, 1958 2 Sheets-Sheet 2 &

INVENTOR:

ANDRE HUET ATTORNEY United States Patent MACHINE FOR STRAIGHTENING TUBE BENDS Andre Hpet, Paris, France, assignor to Combustion Eugineermg, Inc., New York, N.Y., a corporation of Delaware Filed July 7, 1958, Ser. No. 747,054

Claims priority, application France July 17, B57

4 Claims. (Cl. 153-32) The present invention relates to improved apparatus for performing operations on metallic tubing for creating looped elements. In the construction of super-heaters, resuperheaters, etc., constituting parts of steam generating installations, for example, looped tubes are used, that is to say tubes bent several times to form several straight parallel portions connected by 180 deg. return bends, all the loops obtained generally being in a given plane. It is important that all of the straight arms of the looped element be exactly the same length. Now, when the looped element issues from the bend forging machine it happens that the straight parts of the successive loops are of lengths differing as much as a centimeter, and they must be straightened.

The subject of the present invention is a machine for straightening these bends and bringing them to the desired size in a very rapid and economical fashion.

The principle of the machine consists in that, making use of a first bend of a looped element as a fixed point of reference and firmly holding the straight tube length issuing from this bend there is exerted on the following or preceding bend, a compression or traction. This follows heating of the tube along two annular zones on either side of the bend on which the pressure or thrust is exerted. This provokes a shortening or lengthening of the straight length of each bend, provoking to a certain extent, a displacement region of the tube, which finally enables bringing the straight parts of the looped element to the desired dimensions.

The following description when read in conjunction with the attached drawings, given by way of example, will enable understanding of how the invention can be embodied in a machine.

Figure l is a plan view of the machine.

Figure 2 is a side view, partially in section.

Figures 3 and 4 are sections on the lines 33 and 4--4 in Figure l.

The machine which is the subject of the invention is constituted essentially by a table 10, on which the looped tube element or coil B is laid. The element B has, for example, as it leaves the bend forging machine, the form which is seen in Figure 1, that is to say that the straight lengths of the different bends of the coil B do not all have exactly the same length. The straightener embodies the subject of the invention functions to bring the coil B to the desired dimensions, that is to say for example, to make all the return bends tangent to the two end lines AA and BB shown in dotted lines in Figure 1.

On the table there is an adjustable stop 12, mounted to slide on support 14, and be locked in position by a device 16 so that the face 18 of this stop will correspond to the line AA which it embodies. This being the case, a first bend E of coil 8 is brought into contact with face 18 of stop 12 of coil B. From this bend E runs a straight arm F, which ends in the preceding bend G (at the left) which is prolonged in a straight arm H.

The first bend which is to be brought to the desired dimensions, that is to say to be tangent to line BB is bend G. For this purpose there is provided on the machine a grooved matrix 20 which can be displaced with a movement of translation in the direction of arrows D, D (Figure 1) parallel to the straight tube lengths of the coil B. The displacement of the matrix 20 is produced under the influence of piston and cylinder 22, disposed under table 10, and acting by means of the piston rod 23, on a toggle joint linkage 24, one arm 25 of which is articulated to the matrix support 20, and the other 26 to a stop or member 27 adjustable in position along the table 10 by the screw device 28.

If the bend G lies to the left of the line BB (Figure 1) that is to say if the straight arm F is longer than desired, the matrix 20 will engage against the outer end face G of the bend G, and by regulating the position of the adjustable stop 27 so that the movement of the piston rod 23 will provoke a displacement of the matrix 20 in the direction D in such a way that at the end of the travel of the piston the end of the bend G will lie tangent to line BB.

Before performing this operation of compression, the bend G is heated along the two annular zones crosshatched in Figure l, and designated by letters N, N Likewise, the crotch region of the bend G was lightly heated before the operation. In addition, the straight length F of the bend was held immobile by clamping between two jaws 30, 31, which are brought together under the influence of the raising of piston rod 32 of a hydraulic cylinder rod; a jack 33 under the table activated by a knee joint 34 determining the displacement of the jaws 3t 31 in known fashion. As seen in Figure 4, when the two jaws 30, 31 are brought together as far as possible, the straight arm F is firmly held between the semicylindrical grooves 35 provided in the jaws 30, 31 which are not in contact with one another along their inner faces in closed position.

A like device is provided around straight tube length H and is composed of two clamps 40, 41 in a like manner to that of jaws 30, 31 by a jack 42, whose rod 43 acts on a knee joint device 44. However, in contrast to what takes place in the case of the straight arm F, the arm H, when the two jaws 40, 41 are brought as close together as possible (Figure 3), has a certain amount of play inside the semicylindrical grooves of jaws 4G, 41. Under these conditions, these two simply form a guide around tube H and allow the latter to slide, in one direction or the other along its axis.

The coil B, having thus been put in place and heated as stated above, the displacement of the matrix 29 in direction D provokes a compression of the free portion of arm F situated between the jaws 30, 31 which immobilizes it and the matrix 20. However, under the influence of the same compression, arm H will be able to slide between jaws 40, 41. The bend region G of the coil B is then displaced to a certain extent along the straight arms curving into zone N and straighten-ing out in zone N in such a way that the tube F is brought to the desired length and the arm H is slightly lengthened.

When the bend G has been straightened, the operation proceeds to the straightening of the following bend S. For this purpose, the coil B is turned over, for example, deg. on table 10, the bend E still serving as a reference point of application against the fixed stop 12. The bend S then takes the place of bend G, in the previous operation. The straight lengths S and S of this bend S pass between the jaws 3G, 31 on the one hand, 4!}, 41 on the other in the same way as before. The heating of the regions of the bend is also the same as before. Nevertheless, it is to be noted that in the case of the example shown in Figure 1, the straight lengths S S of the bend S are too short with respect to the desired dimensions, that is to say that the bend S lies to the right of line BB. For operations under these conditions, the matrix device 20 comprises a hook 50, which as seen in Figure 2, books behind the crotch 'of'the bend S. The displacement of the jack 22'takes place in the opposite direction D in such a way that this hook 50 exerts a tractionon the crotch of the bend S in the direction D which will bring the end face of the bend S tangent to the line BB. During this operation, heat was applied to the outer end face S of the bend, instead of the crotch in such a way that the hook S applies againsta region of the bend which remains cold. This efiects the dis placement of the bent region S in such a way that the straight part 52, which is to be lengthened, is stretched to the desired length and is brought to thedesired size, that is to say that which separateslines AA and BB. The same operation is then repeated on the successive bends TandVof the coil B. V

The machine is completed by a system of saws 52, 53 for cutting the ends W, X of the outer arms of the coil B to the desired length as soon as the straightening operation is finished and profiting by the operation bringing the arms of the coil to the desired length.

Likewise, we can mount on table the necessary equipment not shown in the drawings to bring in place with a movement of translation, the tools which prepare the ends W, X for welding, or any other operation desired. Thereby, the machine makes possible, in one pass, having perfectly exact dimensions for coilB, and obtaining in series absolutely identical coils, which need only be welded or assembled in order to constitute the superheater or any other desired apparatus.

What I claim is: r

1. Apparatus for adjusting the lengths of the straight tube portions interconnecting 180 return bends in a looped tubular element comprising; a worktable; an adjustably positionable gauging stop on the table engageable by the outer end face of one return bend of the element; means for fixing said gauge stop in position on said table; clamping means on said table inboard of said stop engaging a straight tube length extending at one relatively to said first gauging stop so as to exert a force on said second return bend and the first mentioned tube length extending therefrom so as to adjust the latter to the preselected length determined by the said distance separating said stops.

2. A machine for straightening a looped tube coil comprising; a table equipped with an adjustable gauging stop which can be immobilized; a matrix device adapted to operatively engage a return bend of the coil; means for displacing the said matrix with a movement of translation ending at a fixed point adjustable in advance; two pairs of articulated jaws, one of them gripping and firmly holding one of the straight arms of the coil merging into said bend and the other serving as a guide for the adend from said return bend for fixedly holding said return 7 against said gauging stop; a second stop member operatively engageable with another return bend into which the opposite end of said straight tube length merges, said second stop being movable along said table in a direction parallel to the longitudinal axis of said straight tube length into a predetermined position onsaid table separated from said first gauging stop by a distance corresponding to a predetermined length for the straight tube portions of said looped element; other means on said table between said stops loosely engaging another straight tube length merging into said second return bend for maintaining it parallel with said first mentioned tube length; said second stop being normally in a location beyond its said gauging position where it is operatively engageable by the said second return bend; and means for moving said second gauging stop to its gauging position while engaged with said second return bend and in a direction longitudinally of said element along said table jacent straight arm of the coil; means for operating said jaws; means effecting the displacement of the matrix applying against the bend by means of a device fitted with a knee joint connected on the one hand to the matrix and the other to a stop adjustable in position in such a way that the displacement of the matrices is terminated at a point adjustable in advance. 7

i 3. Apparatus as recited in claim 2 wherein the jaws are operated by means of a jack device actuating the jaws by a knee joint system. 7

4. Apparatus for adjusting the lengths of the straight tube portions interconnecting return bends in a looped tubular element comprising; a worktable; an adjustably positionable gauging stop on the table engageable by the outer end face of one return bend of the element; means for fixing said gauge stop in position on said table; a second stop member engageable with the outer end face of another return bend into which the opposite end of said straight tube length merges; said second stop being movable along said table in a direction parallel to the longitudinal axis of said straight tube length into engagement with said other return bend to move it to a predetermined position .on said table separated from said first gauging stop by a distance corresponding to apredetermined length for the straight tube portions .of said looped element; clamping means on said tablebetween said stops engaging a straight tube length extending at one end from said return bend for fixedly holding said return against said gauging stop; other means between said stops loosely engaging another straight tube length merging into said second return bend for holding it parallel with said first mentioned tube length; said second stop being normally in a locationbeyond its said gauging position where it is operatively engageable by the said second return bend; and means for moving said second gauging stop. to its gaugingposition while engaged with said second return bend and in, a direction longitudinally, ofsaid element alongsaiditable relatively to said first gauging stop so ,as'to, exert a force on said second returnbend and the first mentioned tube length extending therefrom so as to adjust the latter to the preselected length determined-by thesaid distance separating said stops. a r a V References Cited in the. file of patent:

UNITED STATES PATENTS 2,211,204 7 Frank et al. June 21, 1955 M n M;- 

